We, the present inventors, have made study about various deoxy derivatives of an aminoglycoside antibiotic, kanamycin A, and we or some of us, as joint-inventors, have succeeded to synthesize 3'-deoxykanamycin A (U.S. Pat. No. 4,104,372); 3',4'-dideoxykanamycin A (U.S. Pat. No. 4,298,727); 5,2',3',4',4",6"-hexadeoxykanamycin A (U.S. patent application Ser. No. 532,058, now U.S. Pat. No. 4,486,419); and 2'-deoxykanamycin A (U.S. Pat. No. 4,455,419). As a result of our further study, we have also succeeded in synthesizing 2',3'-dideoxykanamycin A which we have never synthesized, by a method comprising preparing a tetra-N-protected and 4',2",4",6"-tetra-O-protected kanamycin A derivative from kanamycin A, converting this derivative into an N,O-protected 2',3'-dideoxy-2'-eno-kanamycin A derivative, reducing this 2'-eno-kanamycin A derivative into an N,O-protected 2',3'-dideoxykanamycin A derivative, and removing all the protective groups from the latter derivative to produce 2',3'-dideoxykanamycin A (our pending Japanese patent application No. 213329/82 and its corresponding Japanese patent application first publication "Kokai" No. 104396/84). We have now been aware of the fact that 2',3'-dideoxykanamycin A was already disclosed in U.S. Pat. No. 4,171,356 issued Oct. 16, 1979. Furthermore, we have been aware that various 1-N-(.omega.-amino-.alpha.-hydroxyalkanoyl) derivatives were synthesized from kanamycins A, B and C as well as kanamycin deoxy-derivatives such as 3'-deoxykanamycin A, 3'-deoxykanamycin B, 3',4'-dideoxykanamycin A, 3',4'-dideoxykanamycin B, 5,2',3',4',4",6"-hexadeoxykanamycin A and the like (see eg. U.S. Pat. No. 3,781,268; U.S. Pat. No. 3,939,143; U.S. Pat. No. 4,001,208; U.S. Pat. No. 4,104,372; U.S. Pat. No. 4,107,424; U.S. Pat. No. 4,297,485; U.S. Pat. No. 4,298,727; U.S. patent application Ser. No. 532,058; and others).
Now, we have made further research in an attempt to provide such a new useful derivative of 2',3'-dideoxykanamycin A which is active against various resistant-strains of bacteria and which is also active against such resistant bacteria as is expected to occur in the future owing to extensive use of known aminoglycoside antibiotics and known semi-synthetic aminoglycoside antibiotics in clinics. We have now succeeded in synthesizing 2',3'-dideoxykanamycin A derivative, 1-N-(L-4-amino-2-hydroxybutyryl)-2',3'-dideoxykanamycin A and 1-N-(L-3-amino-2-hydroxypropionyl)-2',3'-dideoxykanamycin A, and have now confirmed that each of these compounds is a new semi-synthetic aminoglycoside antibiotic exhibiting a useful high antibacterial activity against various resistant bacteria.